What Are The Chances Of Pregnancy Inspite Of Taking Plan B?

Hi my name is kenisha. I was wanting to know if there is a possibility that i might be pregnant? My last cycle started the 2nd of may and went off the 9th of may. My boyfriend came down to see me on the 14th 15th and 16th we had unprotected sex. Within one day we had unprotected sex 3 times on the 2nd day i took one plan b tablet. Then we contiune to have unprotect sex. On the 26th of may i stated bleeding lightly not my regular cycle of about two days. And now i still been having lower stomach crampin as if its about to come on again. Just want to know if its a possibiltiy that i might be just to be on the safe side.